Moffat previously revealed that the US network had approached him about remaking the BBC's Sherlock, before pressing on with their own Sherlock Holmes update.
"We weren't ready to do [a US remake] yet," the writer explained to IGN. "[CBS] said, 'We're great people to come to, we're full of integrity', - a few weeks later, we discovered they were just going ahead and doing it anyway.
"So that was another example of what happens in LA television, I suppose. I wasn't very impressed by it. I haven't had good experiences in general with that lot."
Moffat criticised the network's conduct, calling it "pretty remarkable behaviour".
"It's tough," he explained. "If [Elementary is] bad, it debases the coinage of our show [or] if it's too like our show, we'll have to take action."
Moffat recently told Digital Spy that he has not seen any clips from Elementary, insisting that his previous quotes about the show have been "rather exaggerated".
"I haven't seen it, so I can't really comment," he said. "I think everyone's very anxious for me to have a go at it, and I'm really not."
Elementary will air on Thursdays at 10/9c on CBS this fall.
> Steven Moffat on Elementary: 'CBS have changed Sherlock too much'
Watch a trailer for Elementary below: